CHASSIS FOR A RAIL VEHICLE

Abstract

A chassis for a rail vehicle includes a chassis frame supported on at least first and second wheelsets and one A-frame linkage per wheelset on both sides of the chassis for horizontal axle guidance of the wheelset. Each A-frame linkage is connected in an articulated manner to one of two axle bearings of a wheelset by a wheelset-side bearing and to the chassis frame by two frame-side bearings. At least one of the bearings per A-frame linkage has a hydraulic bushing with variable longitudinal rigidity. The hydraulic bushing has at least one fluid chamber fillable with hydraulic fluid so that in the fluid chamber a hydraulic pressure can form for adjusting longitudinal rigidity. An acceleration sensor per axle bearing measures wheelset acceleration and an adjustment device adjusts hydraulic pressure in at least one of the fluid chambers depending on the measured wheelset acceleration.

Claims

1-12. (canceled)

13. A chassis for a rail vehicle, the chassis comprising: a chassis frame having two sides; at least one first wheelset and at least one second wheelset supporting said chassis frame, each of said wheelsets having a respective axle and two respective axle bearings; A-frame linkages each disposed on a respective one of said sides of said chassis frame for horizontal guidance of said axle of a respective one of said wheelsets; wheelset-side bearings each forming an articulated connection of a respective one of said A-frame linkages to a respective one of said two axle bearings, and two frame-side bearings each forming an articulated connection of a respective one of said A-frame linkages to said chassis frame; at least one of said bearings connected to each respective A-frame linkage having a hydraulic bushing with a variable stiffness, said hydraulic bushing having at least one fluid chamber to be filled with a hydraulic fluid, permitting a hydraulic pressure to form in said at least one fluid chamber for adjusting a longitudinal stiffness; acceleration sensors each being associated with a respective one of said axle bearings for measuring an acceleration of a respective wheelset; and an adjustment device for adjusting the hydraulic pressure in at least one of said fluid chambers as a function of the measured wheelset acceleration.

14. The chassis according to claim 13, wherein said adjustment device is configured to actively impose a turning moment on one of said wheelsets associated with said at least one fluid chamber by adjusting the hydraulic pressure in said at least one fluid chamber.

15. The chassis according to claim 13, wherein said at least one bearing having said at least one fluid chamber is said wheelset-side bearing.

16. The chassis according to claim 13, wherein said adjustment device has a pressure reservoir to be connected to said at least one fluid chamber.

17. The chassis according to claim 13, wherein said adjustment device has a pressure generation device to be connected to said at least one fluid chamber.

18. The chassis according to claim 13, wherein: said at least one fluid chamber of said hydraulic bushing includes a fluid chamber disposed outwardly in a longitudinal direction and a fluid chamber disposed inwardly in the longitudinal direction; said outwardly and said inwardly disposed fluid chambers lie opposite one other and can be filled with hydraulic fluid; fluid channels are each connected to a respective one of said fluid chambers for an inward or outward flow of hydraulic fluid into or out of said respective fluid chamber; and said adjustment device is hydraulically coupled to said fluid channels and is configured to adjust an inward or outward flow of hydraulic fluid to permit the hydraulic pressure in said fluid chambers to be adjusted by using outflows or inflows of hydraulic fluid.

19. The chassis according to claim 18, wherein: said hydraulic bushing is one of a plurality of hydraulic bushings disposed on said sides of said chassis frame; said fluid channels include external fluid channels interconnecting said hydraulic bushings disposed on the same side of said chassis frame; said fluid chambers include a fluid chamber of said first wheelset lying outside and a fluid chamber of said second wheelset lying inside being hydraulically coupled to each other, and a fluid chamber of said first wheelset lying inside and a fluid chamber of said second wheelset lying outside being hydraulically coupled to each other; and said adjustment device is hydraulically coupled to said external fluid channels.

20. The chassis according to claim 19, wherein: said hydraulic bushings each have a respective internal fluid channel through which said fluid chamber lying outside and said fluid chamber lying inside on the same hydraulic bushing are hydraulically coupled to each other; and said adjustment device includes on/off valves each being associated with a respective one of said internal fluid channels for adjusting a flow of hydraulic fluid through said internal fluid channel.

21. The chassis according to claim 13, which further comprises a pressure sensor for measuring a hydraulic pressure in one of said fluid chambers.

22. A method for operating a chassis for a rail vehicle, the method comprising the following steps: providing a chassis including: a chassis frame having two sides; at least one first wheelset and at least one second wheelset supporting the chassis frame, each of the wheelsets having a respective axle and two respective axle bearings; A-frame linkages each disposed on a respective one of the sides of the chassis frame for horizontal guidance of the axle of a respective one of the wheelsets; wheelset-side bearings each forming an articulated connection of a respective one of the A-frame linkages to a respective one of the two axle bearings, and two frame-side bearings each forming an articulated connection of a respective one of the A-frame linkages to the chassis frame; at least one of the bearings connected to each respective A-frame linkage having a hydraulic bushing with a variable stiffness, the hydraulic bushing having at least one fluid chamber to be filled with a hydraulic fluid, permitting a hydraulic pressure to form in the at least one fluid chamber for adjusting a longitudinal stiffness; acceleration sensors each being associated with a respective one of the axle bearings for measuring an acceleration of a respective wheelset; and an adjustment device for adjusting the hydraulic pressure in at least one of the fluid chambers as a function of the measured wheelset acceleration; measuring a wheelset acceleration for each wheelset by using the acceleration sensors; and adjusting the hydraulic pressure in at least one of the fluid chambers as a function of the measured wheelset acceleration.

23. A rail vehicle, comprising a chassis according to claim 13.

24. A non-transitory computer-readable medium with instructions stored thereon, that when executed by a processor, perform the steps of claim 22.

Description

[0048] The characteristics, features and advantages of this invention described above, together with the way and manner in which they are achieved, will become more clearly and more plainly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing, wherein

[0049] FIG. 1 shows a plan view of a two-axle exemplary embodiment of the inventive chassis,

[0050] FIG. 2 shows a plan view of a three-axle exemplary embodiment of the inventive chassis,

[0051] FIG. 3 shows a partially sectioned side view of an A-frame linkage,

[0052] FIG. 4 shows a plan view of the A-frame linkage as shown in FIG. 3,

[0053] FIG. 5 shows a plan view of another two-axle exemplary embodiment of the inventive chassis,

[0054] FIG. 6 shows the chassis as shown in FIG. 5, with further details,

[0055] FIG. 7 shows the chassis as shown in FIG. 1, with further details,

[0056] FIG. 8 shows a flow diagram of a method for operating a chassis, and

[0057] FIG. 9 shows a rail vehicle.

[0058] In what follows, it has been possible to use the same reference marks for the same features. Furthermore it has been determined that, for the sake of overall clarity, not all the reference marks for individual features will be shown in all the drawings.

[0059] A chassis 1 in accordance with the invention, on which a carriage body, not shown, of a rail vehicle, for example a locomotive, has a sprung support so that it can rotate about a vertical axis, has as shown in FIG. 1 and FIG. 2 a chassis frame 2. The chassis frame 2 is supported at least on a first wheelset 3 and a second wheelset 4, which are together designated in what follows as wheelsets 3 and 4. Each of the wheelsets 3 and 4 has two rail wheels 5 which are joined by a wheel axle 7 mounted in two axle bearings 6. For the purpose of horizontal guidance of the wheelsets 3 and 4, each of these is linked onto the chassis frame 2 on both sides of the chassis via A-frame linkages 8. Here, each of the A-frame linkages 8 has articulated linkages to an axle bearing 6 by a bearing 9 on the wheelset side and to the chassis frame 2 by two bearings 10 on the frame side. The frame-side bearings 9 have elastomer bushings 11 with constant longitudinal and lateral stiffness, and the wheelset-side bearing 10 has hydraulic bushings with a constant lateral stiffness and alterable longitudinal stiffness. The bearings 9 and 10 of each A-frame linkage 8 are arranged in each case on the corners of a horizontally oriented isosceles triangle, the apex of which is formed by the wheelset-side bearing 9 and the base by the frame-side bearings 10. The bearings 9 and 10 of each A-frame linkage 8 are arranged in each case on the corners of a horizontally oriented isosceles triangle, the apex of which is formed by the wheelset-side bearing 9 and the base by the frame-side bearings 10. Unlike the two-axle chassis 1 shown in FIG. 1, a three-axle chassis as shown in FIG. 2 has a third wheelset 13, which in the longitudinal direction X is arranged between the first wheelset 3 and the second wheelset 4, and is joined with the chassis frame 2. When the rail vehicle is traveling round a curve, the outer wheelsets 3 and 4 are aligned radially to the arc of the track, indicated in FIG. 1 and FIG. 2 by a dash-dot line. For this purpose, the hydraulic bushings 12 have a low longitudinal stiffness at low travel speeds, while at high travel speeds on largely straight line tracks they have a high stiffness, which leads to a high ride stability. This longitudinal stiffness can be adjusted, as explained below in more detail. For this purpose, acceleration sensors and an adjustment device are provided, as is illustrated and described below in conjunction with FIGS. 6 and 7.

[0060] As shown in FIG. 3 and FIG. 4, each of the A-frame linkages 8 has a linking body 14, the joining web 15 of which extends horizontally and joins together two smaller linkage eyes 16 for accommodating elastomer bushings 11 and a larger linkage eye 17 for accommodating the hydraulic bushing 12. The linking body 14 can be in the form of a cast part or a forged part or a milled part. Optionally, formed onto and protruding from the side edges of the linking web 15 which join the larger linkage eye 17 to the smaller linking eyes 16 are vertical joining ridges 18. Each elastomer bushing 11 has an inner bearing shell 19, an outer bearing shell 20 and an elastomer bushing 21 embedded between them. Because of the rotationally symmetrical structure of the elastomer bushing 11, it has a constant stiffness in the longitudinal direction X and the lateral direction Y. The outer bearing shell 20 sits in the smaller linkage eye 16, while a vertically oriented bearing bolt 22 passes through the inner bearing shell 19. On each of the two ends of the bearing bolt 22 which project out of the inner bearing shell 19 there are two planar seating surfaces, lying parallel to each other, into the face of which is worked in each case a horizontally oriented through-hole 23. These through-holes 23 provide for the fixing device 24 to pass through them, to join the frame-side bearing 10 to the chassis frame 2 above and below the elastomer bushing 11. Each hydraulic bushing 12 also has an inner bearing shell 25, an outer bearing shell 26 and embedded between these a ring-shaped elastomer element 27. The outer bearing shell 26 sits in the larger linkage eye 17, while a bearing bolt 28 passes through the inner bearing shell 25 vertically. The bearing bolt 28 has a vertically-oriented through-hole 29 through which the fixing device 30, for joining the bearing 9 on the wheelset side to the axle bearing 6, passes coaxially through the hydraulic bushing 12. On sides which are opposite to each other in the longitudinal direction X, the elastomer element 27 and the outer bearing shell 26 form two segment-shaped hollow spaces, of which the hollow space facing the elastomer bushings 11 forms a fluid chamber 31 on the inner side and the hollow space facing away from the elastomer bushings 11 forms a fluid chamber 32 on the outer side. The fluid chambers 31 and 32 are linked to each other by an internal fluid channel 33, and are filled with a hydraulic fluid. By this means, the fluid chambers 31 and 32 on the inner and outer sides are hydraulically coupled in such a way that hydraulic fluid which flows out of one of the fluid chambers 31 or 32 due to an externally imposed pressure flows into the other fluid chamber, 32 or 31. The imposed pressures arise from guidance forces between the axle bearings 6 of the wheelsets 3 and 4 and the chassis frame 2, which are transmitted by the A-frame linkages 8 and can lead to an exchange of fluid between the fluid chambers 31 and 32 in the hydraulic bushings 12. In accordance with the invention, this exchange of fluid is actively influenced, as explained further below.

[0061] What is critical for the longitudinal stiffness c (on the assumption that no active influence is exercised on the fluid flows) of the hydraulic bushings 12 is here the frequency f at which lateral accelerations are evoked in the elastomer element 27 from outside by the hunting oscillations of the wheelsets 3 and 4. Apart from a high lateral stiffness, the hydraulic bushings 12 have a variable longitudinal stiffness c which is dependent on the excitation frequency, the nature of which is indicated in FIG. 5. Low frequencies f, which occur at low travel speeds of the rail vehicle, for example while traversing a curve, are associated with a low longitudinal stiffness c.sub.low; the bearings 9 on the wheelset side are then soft, so that a radial adjustment of the wheelsets 3 and 4 is possible on the track curve by a fluid exchange. At high travel speeds of the rail vehicle, when traveling in a straight line, high excitation frequencies f arise, which are associated with a high longitudinal stiffness c.sub.high; the bearings 9 on the wheelset side are then hard, so that the ride stability of the chassis 1 is increased. The speed of the fluid exchange between the fluid chambers 31 and 32 here depends on the flow resistance of the internal fluid channel 33, which is essentially determined by its path and cross-sectional area.

[0062] In the form of embodiment as shown in FIG. 5, the fluid chambers 31 and 32 are not joined internally in a hydraulic bushing, but via external fluid channels 34 which can be made as rigid hydraulic piping or flexible hydraulic hose. The hydraulic bushings 12 which are arranged on the same side of the chassis are here connected by two external fluid channels 34 in such a way that the fluid chamber 32 which lies outside on the first wheelset 3 is hydraulically coupled with the fluid chamber 31 which lies on the inside on the second wheelset 4, and the fluid chamber 31 which lies on the inside on the first wheelset 3 with the fluid chamber 32 which lies on the outside on the second wheelset 4. This coupling is effected on the two sides of the chassis symmetrically relative to the longitudinal direction, thereby improving the radial setting of the wheelsets 3 and 4 on track curves and ensuring the necessary high longitudinal stiffness c when starting up with high tractive force or when braking, as applicable. During the start-up or braking of the wheelsets 3 and 4, the bearings 9 on the wheelset side are subject to forces with the same sense, so that no fluid exchange arises between the coupled fluid chambers 31 and 32the bearing 9 has a hard reaction. When traversing curves, the forces which arise have the opposite sense, so that hydraulic fluid is exchanged between the coupled fluid chambers 32 lying on the inside and on the outside, and because of the soft reaction of the bearings a radial adjustment of the wheelsets 3 and 4 can occur. The advantage of this concept consists in a good transmission of pull/push forces.

[0063] In the embodiments described above the assumption has been made that the fluid flows in or out of the fluid chambers, as applicable, solely because of the wheelset guidance forces. However, in accordance with the invention provision is made that active influence is exercised on the flow behavior of the hydraulic fluid. This will be explained in more detail in what follows.

[0064] FIG. 6 shows the chassis 1 as in FIG. 5, with further details.

[0065] Thus, drawn in FIG. 6 are the acceleration sensors 601 which are designed to measure an acceleration of the wheelset. For this purpose, an acceleration sensor 601 is provided for each axle bearing 6. The acceleration sensors 601 measure an acceleration in the x- and y-direction, together with a rotational acceleration about the z-axis. Correspondingly, the acceleration sensors 601 output acceleration signals 603. This is indicated symbolically by the arrows with the reference marks 603.

[0066] The acceleration signals 603 are fed to a regulatory device 605. This filters the acceleration signals 603, in particular in real time, as a function of the stiffness relationships of the A-frame linkages 8, of the hydraulic bushings 12 and the individual pipes of the hydraulic system, that is in particular the external channels 34, where these stiffness relationships are stored in the regulatory device 605 as benchmarks, so that the filtered acceleration signals can be used as the basis for regulation of the longitudinal stiffness. From the accelerations thus filtered and appropriate setpoint values, the regulatory device 605, which can for example be in the form of a PI regulator, forms a difference signal which supplies the regulating variable for a pressure generating device 607, which comprises a hydropulser, not shown, and a pressure generator, not shown. Together with a pressure generator, the hydropulser forms a hydraulic pressure signal, which is suitable for influencing highly dynamic hunting oscillations of the wheelsets 3 and 4 and to influence accordingly their setting on the track. For a suitable switching frequency (, which is determined) of the fluid chambers 31 and 32 one can thereby, when the vehicle's travel is unstable, advantageously stabilize the wheelsets 3 and 4 by means of the A-frame linkages 8 and hydraulic bushings 12 by imposing a frequency pattern which is counter-phase with the hunting oscillations. In particular, on sharp track curves one can then, by suitable hydraulic switching of the fluid chambers 31 and 32, effect active steering of the wheelsets 3 and 4 for the purpose of optimizing the track guidance and minimizing wear of the wheel running surfaces. The suitable switching frequency is determined, in particular, as a function of the measured wheelset accelerations.

[0067] That is to say, the pressure generation device 607 can set a hydraulic pressure in the fluid chambers 31 and 32 of the individual hydraulic bushings 12. This, in particular, as a function of the measured acceleration signals 603. For this purpose, the regulatory device 605 comprises a signal filter for the acceleration signals 603, in particular a real-time signal filter. In particular, the regulatory device 605 comprises a signal computer with a measured value converter, in particular a real-time signal computer with a measured value converter. The regulatory device 605 comprises in addition a difference calculator with a PI regulator and a setpoint value output for a pulse signal converter. Hence the regulatory device 605 comprises in particular a pulse signal converter with a valve control unit for controlling valves, in particular on/off valves. For the sake of clarity, these valves are not shown in FIG. 6.

[0068] The pressure generation device 607 comprises in addition a hydraulic pulser, which works as an energy converter and generation unit for the required control pulse pattern and for the hydraulic pressure for the hydraulic bushings 12 in the A-frame linkages 8. In one form of embodiment, which is not shown, a separate pressure generator and/or a separate pressure reservoir are provided, to ensure the required hydraulic pressure level for an active stability regulation and steering of the wheelsets 3 and 4.

[0069] In one form of embodiment, which is not shown, pressure monitoring is provided, with one pressure sensor for each coupled fluid chamber 31, 32. By this means, a diagnosis is advantageously made possible in the event of a failure, a leakage.

[0070] So, in FIG. 6 the fluid chambers 31, 32 in the one and same hydraulic bushing 12 have no hydraulic connection between them. Rather they are coupled to each other as described above in conjunction with FIG. 5. This advantageously results in the possibility of exercising active hydraulic control over the forces and accelerations and turning moments which result because of the wheelset guidance forces, and thereby to actively influence the hunting oscillations of the wheelsets 3, 4 which inherently arise on the track. In doing this, the fluid chambers 31, 32 of the hydraulic bushings 12 on the A-frame linkages 8 of the wheelsets 3, 4 are in each case switched together in such a way that the hydraulic pressure prevailing in them effects either a stiffening or a softening of the hydraulic bearings.

[0071] The regulatory device 605 and the pressure generation device 607 form an adjustment device for setting a hydraulic pressure in the fluid chambers 31, 32.

[0072] FIG. 7 shows the chassis 1 as shown in FIG. 1, with further details.

[0073] Analogously to FIG. 6, here again those individual acceleration sensors 601 are now shown which feed appropriate acceleration signals 603 to the regulatory device 605. This latter is constructed, in particular, analogously to the regulatory device 605 as shown in FIG. 6. Reference can be made to the appropriate explanations.

[0074] In the forms of embodiment shown in FIG. 7, the individual fluid chambers 31, 32 of the one and same hydraulic bushing 12 are only coupled hydraulically between each other. The fluid chambers 31, 32 of the hydraulic bushings 12 are, however, not hydraulically coupled between each other. This is unlike the hydraulic coupling as shown in FIG. 6. For the hydraulic coupling of the fluid chambers 31, 32 of the one and same hydraulic bushing 12, channels 701 are provided which connect the fluid chambers 31, 32 of the hydraulic bushings 12 between each other. Here an internal fluid channel 33 can, for example, be provided, analogously to FIG. 4. Provision is made in accordance with the invention for an on/off valve 703 to be provided in the channels 701 or in the internal fluid channel 33, as applicable, which can thus adjust a through-flow or a flow resistance between the two fluid chambers 31, 32 for a hydraulic fluid. Thus, for example, the on/off valve 703 can be closed, so that no connection exists between the fluid chambers 31, 32. In particular, the on/off valve 701 can be open, so that a hydraulic connection exists between the fluid chambers 31, 32. These on/off valves 703 are controlled by means of control signals 705. These control signals 705 are formed by the regulatory device 605. In a way analogous to the embodiments in conjunction with FIG. 6, the regulatory device 605 forms these control signals 705 on the basis of the acceleration signals 603. Here again, the acceleration signals 603 detected by the acceleration sensors 601 are filtered and converted for the regulator in real time and as a function of stiffness relationships which are stored in the regulatory device 605 for the A-frame linkage 8, the hydraulic bushings 12, the on/off valves 703 and the connecting pipes, in particular the channels 701 or the internal channel 33, as applicable. The regulatory device 605 comprises, for example, a PI regulator, and from the measured and filtered accelerations and the appropriate setpoint prescriptions forms a difference signal which is the regulatory variable for a control device, not shown here, for the on/off valves 703. In this form of embodiment with the on/off valves 701, the function of turning moment damping makes possible in each case softening or stiffening of the two axle linkages on the wheelset 3, 4 which is out of phase with the hunting oscillation, and thereby actively damps a highly dynamic hunting oscillation of the wheelsets 3, 4. This form of embodiment thus influences in an advantageous way the radial setting behavior on the track. With a suitable switching frequency (, which is determined,) for the hydraulic fluid chambers 31, 32 one can thereby advantageously effectively damp the frequency of the hunting oscillation when the vehicle's ride is unstable, and stabilize the running of the wheelset. The suitable switching frequency is determined, in particular, as a function of the measured wheelset accelerations.

[0075] Analogously to FIG. 6, here too it is possible to provide, in a form of embodiment for pressure monitoring which is not shown, a pressure sensor for each coupled fluid chamber 31, 32. Here again, the regulatory device 605 comprises a signal filter, a real time signal filter, a signal computer with measured value converter, in particular a real-time signal computer with measured value converter. The regulatory device 605 comprises in addition a difference calculator with a PI regulator and a setpoint output for a pulse signal converter. Hence the regulatory device 605 comprises in particular a pulse signal converter, and a valve control device for controlling the on/off valves 703. Further, the form of embodiment as shown in FIG. 7 comprises a hydraulic turning moment damper, in the form of the on/off valves 703 on the hydraulic bushings 12 in the A-frame linkage 8, for active stability regulation of the wheelsets 3, 4.

[0076] Thus the on/off valves 703 together with the regulatory device 605 form an adjustment facility for adjusting a hydraulic pressure in the fluid chambers 31, 32.

[0077] Hence, the inventive thinking lies in particular in a simple application of the previously proven concept of an A-frame linkage in the chassis and its equipping with hydraulic bushings together with their force-related regulation by the influencing and changing, for example imposition, of the hydraulic pressure level in their fluid chambers for the purpose of actively influencing the linkage characteristics of the axle linkages on the wheelsets of the chassis, and for the purpose of utilizing an active stability regulation by the imposition of a pulse pattern which is counter-phase with the hunting oscillation of the wheelset.

[0078] Provision is thus made to generate active control forces by the use of a hydraulic pulser. In addition, provision is made for the use of acceleration sensors, real-time signal filters, real-time signal computers together with measured value converters for the purpose of setpoint output for the regulatory device, with difference formers and pulse signal converters for the hydraulic controller and the actuators, in particular the on/off valves. Hence, in accordance with the invention provision is made for the use of hydraulically coupled wheelsets by appropriate hydraulic connection and actuation of the fluid chambers in the hydraulic bushings on the A-frame linkages to steer the wheelsets in the chassis. Advantageously, in accordance with one form of embodiment, provision is made for the application of pressure monitoring, by means of pressure sensors on the coupled fluid chambers, as a safety facility in the event of a failure of the hydraulic bushings and in the case of impermissible leakages in the hydraulic system of the active chassis control. In accordance with the invention, in accordance with one form of embodiment, the formation of an active turning moment damper is advantageously provided for stabilizing the wheelset running. The active chassis linkage and the stability regulation, together with the active turning moment damper, can be applied for single and multi-axle chassis, for undriven and driven chassis, for example bogies.

[0079] FIG. 8 shows a flow diagram for a method of operating a chassis in accordance with the invention. In accordance with a step 801, a wheelset acceleration is measured for each wheelset by means of the acceleration sensors. In a step 803, the hydraulic pressure in at least one fluid chamber is adjusted as a function of the measured wheelset acceleration.

[0080] FIG. 9 shows a rail vehicle 901 which comprises the inventive chassis 1.

[0081] Although the details of the invention have been more closely illustrated and described by the preferred exemplary embodiments, the invention is not restricted by the examples disclosed and other variants can be derived from it by a specialist without going outside the scope of protection of the invention.